THIS invention relates to a process for the production of alcohols, typically alcohols in the detergent range.
Detergent range alcohols are alcohols, usually in the C8 to C20 range, (i.e. from 8 to 20 carbon atoms in the molecules) that are useful in the manufacture of detergents and surfactants.
Detergent alcohols are commercially produced by distilling a desired cut of olefins and paraffins from an olefin rich feed. The olefins are then converted to alcohols by hydroformylation. Paraffins are inert to the hydroformylation reaction and form part of the product. Because it is difficult to separate the alcohols from paraffins in the product where the boiling points of the alcohols and paraffins are similar or overlap, it is an accepted practice to distill a narrow-cut of olefins containing a high concentration of two or less carbon numbered olefins and its associated paraffins. Conversion of the olefins to alcohols increases the boiling points of the olefins relative to the paraffins, thereby facilitating easy separation of the alcohols from the associated paraffins.
Detergent range alcohols may be produced from olefins contained in the condensation product of a high temperature or a low temperature Fischer-Tropsch reaction preferably using an iron based catalyst. Typically a feed stream from such a Fischer-Tropsch reaction consists predominantly of olefins. Sasol commercially operates a process in which the feed stream from the Fischer-Tropsch reaction is fractionated into a stream containing olefins in predominantly the 2C range, which is introduced to a hydroformylation reactor in which the olefins are converted to alcohols and/or aldehydes. The alcohols and/or aldehydes are then separated from paraffins in the stream. The resulting alcohols and/or aldehydes are predominantly in the 2C range.
In order to increase the scale of such a hydroformylation plant, it would be beneficial to use a broader cut of carbon number olefins, for example olefins in the 3C or even 4C range. However, it is well known that the boiling points of the alcohols and/or aldehydes in the hydroformylation product overlaps that of the unreacted parrafins, leading to difficulties in separation of the paraffins from the alcohol and/or aldehyde product.
It is an object of this invention to provide an improved method for the production of alcohols, typically used as detergent precursors.